The present invention relates to a sheet feeding apparatus equipped with a sheet transport device for feeding sheets stacked on a supply tray. More specifically, it relates to a stopper mechanism to restrict the leading edges of sheets stacked on a supply tray.
Conventionally, in the sheet feeding apparatuses mounted on the sheet transport apparatuses, such as automatic document feeders, copy machines or printers for feeding sheets, such as originals or copy sheets stacked on a supply tray, sheets are placed in a condition that the stopper member protrudes in the supply tray, and a rising and lowering draw-out roller is lowered to touche the sheets, while at the same time, the stopper is retracted from the sheet supply entrance. The sheets are drawn by the rotation of the draw-out roller and are separated into a single sheet by separating means comprised of a supply roller and a separating member.
It is commonly known for the stopper member in a sheet feeding apparatus to have a structure in which the stopper member is related with the rising and lowering of the draw-out roller to be moved into and out of the sheet supply entrance. When the draw-out roller is at a raised position and the sheets are placed on the sheet supply tray, the stopper member protrudes into the sheet supply entrance or path to restrict the leading edges of the sheets thereby preventing the sheets from entering inside the machine. When the draw-out roller is at a lowered position and the sheets are being drawn into the machine, the stopper member retracts from the sheet supply entrance to allow the sheets to advance into the machine.
However, when a sheet is jammed inside the machine in the sheet supply apparatus, such as the one just described, the draw-out roller is controlled to rise to the sheet setting position to enable the resetting of the sheet after the jammed sheet has been cleared from the inside of the machine. The control to raise to the sheet setting position when removing the jammed sheet is necessary not only to enable a resetting of the sheet, but also to touch the draw-out roller against the sheet surface with the prescribed pressure.
When the draw-out roller is controlled to raise to the sheet setting position, the stopper member, associated with the raising of the draw-out roller, is forcibly protruded into the sheet supply entrance. At this time, if the sheets at the sheet supply entrance that are not jammed are not removed and placed on the sheet supply tray, the leading edge of the stopper member forcibly protruded will push the sheet causing the problem of damaging the sheet. Particularly, if thin sheets are being used, they can be torn.
Also, because the stopper member described above is structured to appear and disappear into and out of the sheet supply entrance by the drive actuated by a drive motor or a solenoid, such mechanism is complex and expensive.
An object of the present invention is to provide a sheet feeding apparatus that has a simple mechanism and is low cost and which does not damage sheets when the stopper member enters the sheet supply entrance while the sheets are on the sheet supply tray.
To attain the objectives of the present invention, the sheet feeding apparatus separates the sheets stacked on a sheet stacking tray into a single sheet for feeding the sheets to a predetermined sheet processing position, and includes draw-out means that touches the uppermost sheet on the sheet supply tray for drawing out sheets, support means for support the draw-out means to rise and lower, sheet feeding means for separating the sheets drawn out by the draw-out means into a single sheet and feeding the same, stopper means that rotates to a first position to restrict the leading edges of the sheets stacked on a sheet supply tray and to a second position to allow the sheets drawn out by the draw-out means to pass through, and displacement means to displace the stopper means associated with the lowering action of the draw-out means to a third position between the first position and second position to displace the stopper member to the third position from the first position using the displacement means. The stopper means moves from the third position to the second position by the leading edge of the sheets drawn out by the draw-out means.
Also, the sheet transport apparatus separates originals or sheets stacked on a sheet supply tray into a single sheet, feeds it to the reading position wherein the desired images on the sheet are read, and discharges the sheet read at the reading position to a discharge tray. It is equipped with draw-out means that touches the upper surface of the sheets on the sheet supply tray to draw the originals, and supporting means that supports the draw-out means to rise or lower. Further provided are paper feed means for separating sheets drawn out by the draw-out means into a single sheet for feeding, and a paper feed path formed to extend from the sheet supply tray for guiding the sheet fed by the paper feed means to the reading position. Stopper means is rotationally supported to have a first position disposed at the paper feed entrance of the paper feed path to regulate the leading edge of originals stacked on the sheet supply tray, a second position to allow the sheets drawn out by the draw-out means to pass therethrough, and a third position between the first and second positions.
Also disposed are regulating means to regulate the movement of the stopper means at the first position for regulating the leading edges of the sheets, displacement means to displace the stopper member in association with the dropping movement of the draw-out means from the first position to the second position, and release means to displace the stopper means from the first position to the third position by the displacement means. This also acts to release the regulation of the paper feed of the regulating means by displacing the stopper means from the third position to the second position by the leading edges of the sheets drawn by the draw-out means.